On 21/03/2011 17:38, V G wrote:
> On Sat, Mar 19, 2011 at 5:15 PM, V G<.....x.solarwind.xKILLspam@spam@gmail.com> wrote:
>
>> Hi, I like the idea of direct to PCB resist printing, but don't really have
>> the time to modify my own printer. Does anyone know of where I can get a
>> pre-modified printer for this purpose?
>
> Hm. I guess not :(

> On 21/03/2011 17:38, V G wrote:
>> On Sat, Mar 19, 2011 at 5:15 PM, V G<.....x.solarwind.xKILLspam.....gmail.com> wrote:
>>
>>> Hi, I like the idea of direct to PCB resist printing, but don't really have
>>> the time to modify my own printer. Does anyone know of where I can get a
>>> pre-modified printer for this purpose?
>>
>> Hm. I guess not :(
>
> Photo exposure is better.
>
> Iron off laser toner next best. Discussed previously here
>
> Any other print solution will be poor
>

On 21/03/2011 19:53, V G wrote:
> You say photo exposure is best. Would you still say it's the best if
> the method is using positive photo resist spray and developer? Or is
> it only good when using pre-sensitized boards?

Never used the spray on. I imagine the board needs to be very clean. polished and degreased just prior to spray.

On Mon, Mar 21, 2011 at 01:58:58PM -0400, Michael Watterson wrote:
> On 21/03/2011 17:38, V G wrote:
> > On Sat, Mar 19, 2011 at 5:15 PM, V G<EraseMEx.solarwind.xspam_OUTTakeThisOuTgmail.com> wrote:
> >
> >> Hi, I like the idea of direct to PCB resist printing, but don't really have
> >> the time to modify my own printer. Does anyone know of where I can get a
> >> pre-modified printer for this purpose?
> >
> > Hm. I guess not :(
>
> Photo exposure is better.
>
> Iron off laser toner next best. Discussed previously here
>
> Any other print solution will be poor

This is a current topic of interest for me. Basic parameters:

1. Single sided, one off, SMT boards for hobby prototyping. So occasional
processing (not too complicated) and ultra quick turnaround (the faster,
the better, ideally 1 hour or less) are at a premium.

2. Most likely targets are SOIC, 0805/0603 type parts.

3. KiCAD is the development target (may or may not be relevant)

What is the best method using the following priorities (in order):

1. Speed from printing of design to population ready.

2. Process repeatibility both in terms of producing a correct board with
the process and producing repeat boards using the same process. Presume
that this is the occasional hobby board, not a production setup.

3. Cost per board.

In short if I could print chips directly onto the PCB, that would be great.
Impossible, but great. Right now I'm looking at using a PCB hot plate type
setup for soldering. So the faster I can get setup, the faster I can get
finished.

I'm planning on testing both the Toner Transfer and the Photo resist with
precoated boards. Both seem to be about the same amount of time in terms of
speed. Overall the TT method seems to be cheaper as precoated boards seem
to run about 3x the cost. So it seems to me that the real question is
process repeatability.

> I'm planning on testing both the Toner Transfer and the Photo resist with
> precoated boards. Both seem to be about the same amount of time in terms
> of
> speed. Overall the TT method seems to be cheaper as precoated boards seem
> to run about 3x the cost. So it seems to me that the real question is
> process repeatability.

Hi Byron,

I've tried using an XY pen plotter directly to PC board and never got
good enough etch resistance. All over the net there are recommendations
for the RED Staedtler Lumocolor pens but even they are not good enough.

I have used spray-on photoresist. It's OK except for the hairs and dust.
In other words, not good for fine pitch because you will have bad spots.

Laser toner transfer is sensitive to your ironing pressure and
temperature. I always print a border around my artwork to act as a
pressure buffer. It seems to even out the pressure near the edges. Fair
to good results if you have finesse. Prepare for lots of do-overs and
some touchup before and after etch.

Presensitized board works really well. No question, this is the way to
go if you want quality. And unlike the other methods it takes very
little talent. Your first board will be good and every one to follow.

I tend to do toner transfer because I am drawn to how immediate it
seems, and the fact that you don't really need any consumables. But then
after I have ironed on and cleaned off the same board three times before
I get a transfer good enough to etch, I rethink my choice of technology,
wishing I'd used presensitized board instead. And it's not like there
are no consumables, I use acetone to clean the board and lacquer thinner
to remove the toner.

Note to self: Since I don't make more than a dozen boards a year I
should always use the presensitized board.

I started working my way through the presensitized boards the last time I
was on this roller coaster but did not complete the job. Let me run a brief
description of what I have read and see if there are any errors in my
thinking:

2) Bind sheet face down (and flat) to presensitized board. Cover with real
glass as it is transparent to UV. Do this in a low light environment.

3) Expose assembly to UV light. Sunlight will work but a UV light box is
better. Mine is a black light installed in a toolbox. Never got a clear
number on exposure time. Seems to be trail and error but consistent once
you get it to work.

4) Peel the transparancy and there should be a outline image of the circuit
on the board. Run the board through the developer (some say caustic/washing
soda is OK, others hate it. Suggestions?) until the exposed parts a
removed. Do not do it too long or risk undercutting the solid unexposed resist.

5) Etch the board.

6) Remove the rest of the photoresist. A bit unclear here. Is this a light
and develop a second time step? Or a physical process

Should be ready to shake and bake after this.

On this recommendation, I will attempt this method first. There seems to be
repeatability issues with the toner transfer method.

> On Mon, 21 Mar 2011 18:32 -0400, "Byron Jeff" wrote:
>
> > I'm planning on testing both the Toner Transfer and the Photo resist with
> > precoated boards. Both seem to be about the same amount of time in terms
> > of
> > speed. Overall the TT method seems to be cheaper as precoated boards seem
> > to run about 3x the cost. So it seems to me that the real question is
> > process repeatability.
>
> Hi Byron,
>
> I've tried using an XY pen plotter directly to PC board and never got
> good enough etch resistance. All over the net there are recommendations
> for the RED Staedtler Lumocolor pens but even they are not good enough.
>
> I have used spray-on photoresist. It's OK except for the hairs and dust.
> In other words, not good for fine pitch because you will have bad spots.
>
> Laser toner transfer is sensitive to your ironing pressure and
> temperature. I always print a border around my artwork to act as a
> pressure buffer. It seems to even out the pressure near the edges. Fair
> to good results if you have finesse. Prepare for lots of do-overs and
> some touchup before and after etch.
>
> Presensitized board works really well. No question, this is the way to
> go if you want quality. And unlike the other methods it takes very
> little talent. Your first board will be good and every one to follow.
>
> I tend to do toner transfer because I am drawn to how immediate it
> seems, and the fact that you don't really need any consumables. But then
> after I have ironed on and cleaned off the same board three times before
> I get a transfer good enough to etch, I rethink my choice of technology,
> wishing I'd used presensitized board instead. And it's not like there
> are no consumables, I use acetone to clean the board and lacquer thinner
> to remove the toner.
>
> Note to self: Since I don't make more than a dozen boards a year I
> should always use the presensitized board.
>
> Cheerful regards,
>
> Bob
>
>
> --
> http://www.fastmail.fm - A no graphics, no pop-ups email service
>

On 21/03/2011 22:43, Bob Blick wrote:
> Presensitized board works really well. No question, this is the way to
> go if you want quality. And unlike the other methods it takes very
> little talent. Your first board will be good and every one to follow.

I agree totally - I have used spray on photoresist (messy, difficult to get even and contaminant free)
and Toner Transfer (good, but not as accurate/repeatable as photoresist)
With hot etching fluid and agitation you will get fast etching times (~5min) and near board house resolution (we get down to around 0.2mm trace width) after a little practice. Worth investing in a UV light box that gives even exposure, and a decent heated etch tank. However you can get good results with a tray in hot water and a source of UV - I used an old sunlamp to start with, worked perfectly.

When using 'scuffed' shipping label backing and a laminating press,
I've found toner transfer to be very reliable and precise, even using
it for some small BGA work. Posted more details here a long time ago,
if you're interested. The good thing about using the mailing label
backing is that it peels right off, no soaking, scrubbing, or
developing needed. Just my experience.

> Bob,
>
> This analysis was extremely helpful.
>
> I started working my way through the presensitized boards the last time I
> was on this roller coaster but did not complete the job. Let me run a brief
> description of what I have read and see if there are any errors in my
> thinking:
>
> 1) Print mirror of circuit onto transparancy sheet at max toner setting.
>
> 2) Bind sheet face down (and flat) to presensitized board. Cover with real
> glass as it is transparent to UV. Do this in a low light environment.
>
> 3) Expose assembly to UV light. Sunlight will work but a UV light box is
> better. Mine is a black light installed in a toolbox. Never got a clear
> number on exposure time. Seems to be trail and error but consistent once
> you get it to work.
>
> 4) Peel the transparancy and there should be a outline image of the circuit
> on the board. Run the board through the developer (some say caustic/washing
> soda is OK, others hate it. Suggestions?) until the exposed parts a
> removed. Do not do it too long or risk undercutting the solid unexposed resist.
>
> 5) Etch the board.
>
> 6) Remove the rest of the photoresist. A bit unclear here. Is this a light
> and develop a second time step? Or a physical process
>
> Should be ready to shake and bake after this.
>
> On this recommendation, I will attempt this method first. There seems to be
> repeatability issues with the toner transfer method.
>
> Thanks for the input.
>
> BAJ
>
>
> On Mon, Mar 21, 2011 at 06:43:57PM -0400, Bob Blick wrote:
>> On Mon, 21 Mar 2011 18:32 -0400, "Byron Jeff" wrote:
>>
>> > I'm planning on testing both the Toner Transfer and the Photo resist with
>> > precoated boards. Both seem to be about the same amount of time in terms
>> > of
>> > speed. Overall the TT method seems to be cheaper as precoated boards seem
>> > to run about 3x the cost. So it seems to me that the real question is
>> > process repeatability.
>>
>> Hi Byron,
>>
>> I've tried using an XY pen plotter directly to PC board and never got
>> good enough etch resistance. All over the net there are recommendations
>> for the RED Staedtler Lumocolor pens but even they are not good enough.
>>
>> I have used spray-on photoresist. It's OK except for the hairs and dust.
>> In other words, not good for fine pitch because you will have bad spots.
>>
>> Laser toner transfer is sensitive to your ironing pressure and
>> temperature. I always print a border around my artwork to act as a
>> pressure buffer. It seems to even out the pressure near the edges. Fair
>> to good results if you have finesse. Prepare for lots of do-overs and
>> some touchup before and after etch.
>>
>> Presensitized board works really well. No question, this is the way to
>> go if you want quality. And unlike the other methods it takes very
>> little talent. Your first board will be good and every one to follow.
>>
>> I tend to do toner transfer because I am drawn to how immediate it
>> seems, and the fact that you don't really need any consumables. But then
>> after I have ironed on and cleaned off the same board three times before
>> I get a transfer good enough to etch, I rethink my choice of technology,
>> wishing I'd used presensitized board instead. And it's not like there
>> are no consumables, I use acetone to clean the board and lacquer thinner
>> to remove the toner.
>>
>> Note to self: Since I don't make more than a dozen boards a year I
>> should always use the presensitized board.
>>
>> Cheerful regards,
>>
>> Bob
>>
>>
>> --
>> http://www.fastmail.fm - A no graphics, no pop-ups email service
>>

I'd agree with that. The human component is the important
variable. Repeatability and detail is there for the getting

Take these examples

PIC + quad amp + 0805 R and C. Very small text under
the 'JC 3.11' is my note for the board size. It is just about
readable (if you know what it's supposed to read. FWIW
it says, mirrored, 1.85 x 2.65 4.70 6.74 @ 600 dpi)

I read one person's account where he uses a hot-plate with a
weight to apply a known pressure for a known time. That's
something I'd like to investigate. My gauging of iron pressure
is fairly good and but I'd rather it be controlled, for a more
consistent Toner Squash Factor, which causes holes to shrink
and tracks to widen. That said, SOIC 0.05" pitch is quite
easily achievable

On 21/03/2011 23:41, Byron Jeff wrote:
> Bob,
>
> This analysis was extremely helpful.
>
> I started working my way through the presensitized boards the last time I
> was on this roller coaster but did not complete the job. Let me run a brief
> description of what I have read and see if there are any errors in my
> thinking:
>
> 1) Print mirror of circuit onto transparancy sheet at max toner setting.

Tracing paper works just as well (and is cheaper)
The UV gets through fine.

> 2) Bind sheet face down (and flat) to presensitized board. Cover with real
> glass as it is transparent to UV. Do this in a low light environment.
>
> 3) Expose assembly to UV light. Sunlight will work but a UV light box is
> better. Mine is a black light installed in a toolbox. Never got a clear
> number on exposure time. Seems to be trail and error but consistent once
> you get it to work.

Varies with power of light (and I think resist type, so try to stick to one) so a bit of trial and error - Good idea to print a small test board, consisting of traces (with corners) from 1mm down to 0.1mm, a few SMD footprints (TQFP, QFN) and some through hole pads with thin annular rings. Expose a few of these, gradually adjusting time and note down what works best.

> 4) Peel the transparancy and there should be a outline image of the circuit
> on the board. Run the board through the developer (some say caustic/washing
> soda is OK, others hate it. Suggestions?) until the exposed parts a
> removed. Do not do it too long or risk undercutting the solid unexposed resist.

I use Sodium Metasilicate, it is a lot better than Sodium Hydroxide (Caustic Soda)
You don't have to get the timing so accurate (i.e if you leave it in a second too long it won't strip the resist off)

> 5) Etch the board.
>
> 6) Remove the rest of the photoresist. A bit unclear here. Is this a light
> and develop a second time step? Or a physical process

Either - you can shove it under the light again then rinse in developer (I do this way)
Or I think some folk just use an abrasive pad to clean it off, which I do anyway afterwards to clean the copper, then run a bit of isopropyl alcohol over it.
You can actually leave it on too I think - IIRC some resists act as a flux, check the info/documentation on whatever board you buy. Never tried it so not sure how it compares.

> Should be ready to shake and bake after this.
>
> On this recommendation, I will attempt this method first. There seems to be
> repeatability issues with the toner transfer method.

I would verify if the density setting actually does anything. Every
printer is different and on mine it was turning off "economy".

Also you can use cheap 20 LB paper in a pinch if you don't have
transparencies.

I've been told inkjets work OK too, in high quality mode.

> 2) Bind sheet face down (and flat) to presensitized board. Cover with
> real
> glass as it is transparent to UV. Do this in a low light environment.

I've used glass and plexiglass and not noticed a difference. I thought
glass blocked more UV than plastic?

I have had problems peeling it off afterward. The toner sticks a little
bit.

> 3) Expose assembly to UV light. Sunlight will work but a UV light box is
> better. Mine is a black light installed in a toolbox. Never got a clear
> number on exposure time. Seems to be trail and error but consistent once
> you get it to work.

Sunlight is nice because it is very much like a point source and you can
put the printed side out and still get focus. But if you already made a
mirror image that won't work because everything is reversed.

Timing sunlight is near impossible. I made a cumulative timer but never
got the right sensor/filter combination to match the sensitizer.

With a UV box you must get your transparency touching flat on the board
everywhere.

Timing is trial and error, but it is pretty forgiving, 2:1 once you get
in the window.

> 4) Peel the transparancy and there should be a outline image of the
> circuit
> on the board. Run the board through the developer (some say
> caustic/washing
> soda is OK, others hate it. Suggestions?) until the exposed parts a
> removed. Do not do it too long or risk undercutting the solid unexposed
> resist.

When I was teaching we made our own solution with lye. That was before
it got recognized as a component to make meth and consequently harder to
find. Now I use the recommended developer.

> 5) Etch the board.
>
> 6) Remove the rest of the photoresist. A bit unclear here. Is this a
> light
> and develop a second time step? Or a physical process

On Mon, 21 Mar 2011 19:21 -0400, "AK" wrote:
> When using 'scuffed' shipping label backing and a laminating press,
> I've found toner transfer to be very reliable and precise, even using
> it for some small BGA work. Posted more details here a long time ago,
> if you're interested. The good thing about using the mailing label
> backing is that it peels right off, no soaking, scrubbing, or
> developing needed. Just my experience.

Yes, I remember your suggestion about label backing and adopted it,
thank you.
All it takes is to ask someone who uses a UPS printer and then you have
an unlimited supply of backing paper :)

A laminating press would make a big improvement, I'm sure it would make
my boards lots more consistent.

> > 2) Bind sheet face down (and flat) to presensitized board. Cover with
> > real
> > glass as it is transparent to UV. Do this in a low light environment.
>
> I've used glass and plexiglass and not noticed a difference. I thought
> glass blocked more UV than plastic?

Both glass and some plastics absorb UV, but at the thickness tipically used (~1
mm for glass) the absorbance is not too high. More important is that the glass
is "optical quality", without swirls.

>
> I have had problems peeling it off afterward. The toner sticks a little
> bit.
>
> > 3) Expose assembly to UV light. Sunlight will work but a UV light box is
> > better. Mine is a black light installed in a toolbox. Never got a clear
> > number on exposure time. Seems to be trail and error but consistent once
> > you get it to work.

I used a fluorescent lamp at 15-20 cm from the board/mask/glass stack. It was
while ago, but IIRC 75W lamp is OK. Some even reported the use of 100W
incandescent lamp. It might not work with all sensitized boards, I got mine
from Jameco, the brand is DATAK I believe.

> > 6) Remove the rest of the photoresist. A bit unclear here. Is this a
> > light
> > and develop a second time step? Or a physical process

I scrubbed with a scrubber/foam pad sold for kitchen cleaning. As last step,
200-400 grit sandpaper and water rinse. I used purified water for final rinse
since tap water often has too many minerals in it (actually I have never tested
if just tap water is OK, seems easier to just rinse in distilled water any way).
Sergey Drygahttp://beaglerobotics.com

> When using 'scuffed' shipping label backing and a laminating press,
> I've found toner transfer to be very reliable and precise, even using
> it for some small BGA work. Posted more details here a long time ago,
> if you're interested. The good thing about using the mailing label
> backing is that it peels right off, no soaking, scrubbing, or
> developing needed. Just my experience.

On Tue, Mar 22, 2011 at 2:45 AM, V G <KILLspamx.solarwind.xKILLspamgmail.com> wrote:
> On Mon, Mar 21, 2011 at 7:21 PM, AK <RemoveME00TakeThisOuTcase.edu> wrote:
>
>> When using 'scuffed' shipping label backing and a laminating press,
>> I've found toner transfer to be very reliable and precise, even using
>> it for some small BGA work. Posted more details here a long time ago,
>> if you're interested. The good thing about using the mailing label
>> backing is that it peels right off, no soaking, scrubbing, or
>> developing needed. Just my experience.
>
>
> Hi. Where do you get label backing paper?

I began with photo paper as described elsewhere. My experience has
been that a properly prepped backing transfers more cleanly and with
much more ease than paper. In fact, some sheets I've used multiple
times after the transfer. It's likely that you'll get finer details
with a refined optical masking process as described by others, but you
can't beat this toner transfer process for speed, cost, lack of
chemicals, and simplicity

The kind used for overhead transparencies, which have an absolutely glossy surface, and which WILL melt and destroy your printer,
and those that are made of acetate, and which are a bit smoky and have a very fine texture surface for the toner to grab on to.

If in doubt, put a soldering iron to them. The dangerous plastic will melt nearly instantly, and stink, the 'laser' grade will curl but you'll have to apply a fair bit of heat to melt into them.

> I'm a little afraid of using this sheets on my laser printer because their
> surface looks like plastic...
>
> Don't you think there is any risk of fusing it into the printer?
>
>
> Marcelo Fornaso
>
>>Generally free as a result of shipping other items, using this:
>>cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=160516738494
>

On Tue, 22 Mar 2011 15:20 -0700, "Ing. Marcelo Fornaso" wrote:
> I'm a little afraid of using this sheets on my laser printer because
> their
> surface looks like plastic...
>
> Don't you think there is any risk of fusing it into the printer?

With label attached it is intended to run through a printer. I haven't
ever had a problem.

It is too slippery to hold the toner until you scuff it up a little bit
with a tissue or paper towel.

I don't run it full letter size through the printer. I attach a piece
larger than the design on to a sheet of normal paper using a label at
the top of the backing paper. Center the design on the sheet so the
leading edge of the carrier paper has nothing additional on it.
Cheers,

On Tue, 22 Mar 2011 15:20 -0700, "Ing. Marcelo Fornaso" wrote:
> I'm a little afraid of using this sheets on my laser printer because
> their
> surface looks like plastic...
>
> Don't you think there is any risk of fusing it into the printer?

With label attached it is intended to run through a printer. I haven't
ever had a problem.

It is too slippery to hold the toner until you scuff it up a little bit
with a tissue or paper towel.

I don't run it full letter size through the printer. I attach a piece
larger than the design on to a sheet of normal paper using a label at
the top of the backing paper. Center the design on the sheet so the
leading edge of the carrier paper has nothing additional on it.
Cheers,

> I'm a little afraid of using this sheets on my laser printer because
> their
> surface looks like plastic...

Sheesh. Find someplace that uses laser-printable label sheets. Or even buy some. Use any remaining labels as ... labels or something, leaving you with a backing sheet suitable for this sort of toner- transfer. Any laser-printable labels will have a non-melting backing sheet; probably silicone based.

Try the library. Our middle school library prints bar codes on sheets of labels for their new books. This usually doesn't fill up a sheet, and the software doesn't support exact placement of the barcodes on partially filled sheets, so the remaining labels get stamped with the school name/etc for tagging magazines and such. Eventually they're all used up and the backing sheet is thrown away.

Some backing sheets are nicer than others.

I prefer the destructively processed glossy magazine paper route. The reason that the label backing sheet works so well is that toner doesn't stick to it. Which also can mean that it's subject to flaking off somewhere in the process before it gets to your board...

=======

Professional PCB fabrication services get cheaper and cheaper, and more and more convenient to amateurs. Batched hobbyist services (batchPCB, dorkbot) have "solved" the minimum board size problem, so that you're no longer penalized for wanting a very small board. Direct-from-china suppliers (Itead, Seeed) are doing the cheap- prototypes (~$20) with long lead time thing so that you're no longer forced to use a high-priced quick-turn supplier for "prototypes." The only remaining advantage of home fabrication is that simplicity (single sided, 16mil design rules) will get you faster and cheaper. But it's getting harder and hard to justify.

>
> On Mar 22, 2011, at 3:20 PM, Ing. Marcelo Fornaso wrote:
>
> > I'm a little afraid of using this sheets on my laser printer because
> > their
> > surface looks like plastic...
>
> Sheesh. Find someplace that uses laser-printable label sheets. Or
> even buy some. Use any remaining labels as ... labels or something,
> leaving you with a backing sheet suitable for this sort of toner-
> transfer. Any laser-printable labels will have a non-melting backing
> sheet; probably silicone based.
>
> Try the library. Our middle school library prints bar codes on sheets
> of labels for their new books. This usually doesn't fill up a sheet,
> and the software doesn't support exact placement of the barcodes on
> partially filled sheets, so the remaining labels get stamped with the
> school name/etc for tagging magazines and such. Eventually they're
> all used up and the backing sheet is thrown away.
>
> Some backing sheets are nicer than others.
>
> I prefer the destructively processed glossy magazine paper route.
> The reason that the label backing sheet works so well is that toner
> doesn't stick to it. Which also can mean that it's subject to flaking
> off somewhere in the process before it gets to your board...
>
> =======
>
> Professional PCB fabrication services get cheaper and cheaper, and
> more and more convenient to amateurs. Batched hobbyist services
> (batchPCB, dorkbot) have "solved" the minimum board size problem, so
> that you're no longer penalized for wanting a very small board.
> Direct-from-china suppliers (Itead, Seeed) are doing the cheap-
> prototypes (~$20) with long lead time thing so that you're no longer
> forced to use a high-priced quick-turn supplier for "prototypes." The
> only remaining advantage of home fabrication is that simplicity
> (single sided, 16mil design rules) will get you faster and cheaper.
> But it's getting harder and hard to justify.
>
> BillW
>
>

$20 with shipping and tax compared to a few dollars and instant turnaround
times is not hard to justify

> $20 with shipping and tax compared to a few dollars and instant
> turnaround
> times is not hard to justify.

It depends. Couple bucks for blank copper clad. Couple bucks for etchant. Significant bucks for the high-grade ink cartridge (for direct to PCB printing) (which may or may not dry up between PCBs (I hate inkjets!)) or a couple bucks for special transfer paper or transparency paper. Couple bucks for drill bits. Couple bucks for tool to cut the PCB material. Moderate amount for an inkjet printer to modify, or for a laminator, or for an iron, or for a contact exposure frame. Couple buck for other chemicals, sandpaper, etc.

I dunno. I've spent a couple $K for an LPKF (mill) to get that "instant turnaround." But it's not really that "instant", and I'm increasingly uncertain that it was a worthwhile purchase.

> On Wed, Mar 23, 2011 at 1:27 AM, William "Chops" Westfield <KILLspamwestfwspamBeGonemac.com
> > wrote:
>
>> It depends. Couple bucks for blank copper clad.
>>
>
> Agreed.
>
>
>> Couple bucks for etchant.
>>
>
> That's a one time thing. A bottle will last a LONG time. If you use the
> HCL/H2O2 method, you can make it last forever and it's VERY cheap.
>
>
>> Significant bucks for the high-grade ink cartridge (for
>> direct to PCB printing) (which may or may not dry up between PCBs (I
>> hate inkjets!))
>
>
> Or, just a laser printer (that most people have anyway) on label backing
> paper that you can get for free.
>
>
>> or a couple bucks for special transfer paper or
>> transparency paper.
>
>
> It'll last you a lifetime.
>
>
>> Couple bucks for drill bits.
>
>
> Tungsten carbide bits will last you pretty much forever and they're pretty
> cheap.
>
>
>> Couple bucks for tool to cut the PCB material.
>
>
> Again, it'll last you forever.
>
>
>> Moderate amount for an inkjet printer
>> to modify, or for a laminator, or for an iron, or for a contact
>> exposure frame. Couple buck for other chemicals, sandpaper, etc.
>>
>
> Sandpaper costs pennies, most people already have a laser printer, most
> people have a clothes iron.
>
>
>> I dunno. I've spent a couple $K for an LPKF (mill) to get that
>> "instant turnaround." But it's not really that "instant", and I'm
>> increasingly uncertain that it was a worthwhile purchase.
>
>
> So what you only really need is the copper board. Everything is already
> lying around somewhere or will last "forever" or costs pennies.
>

I agree, there is a startup cost, but that cost is very cheap and probably
less than the cost of a decent sized professionally made PCB. I'd seriously
rather make them myself. 30 seconds to print, a few minutes to iron, a few
minutes to etch, a few minutes to drill/sand and there you have it. I can
have a design to end product in 30 minutes (done so a few times already).
And for small things, that's priceless.

When there was a board house up the road I could get free
useable offcuts (A5 or better) of fibreglass and phenolic. Now
they've gone I pay about 16c / sq in for FR4, retail. Much less
if on a/c and I get the tax back. Compared with the hours spent
on the micro and cost for other components, it's a minor part of
the budget. I couldn't count the number of sq in I've etched with
the 5kg (NZ$40 IIRC) of FeCl I bought years ago. It's a lot

'William Chops" Westfield ' <EraseMEwestfwEraseMEmac.com wrote:
> It depends. Couple bucks for blank copper clad. Couple bucks for
> etchant. Significant bucks for the high-grade ink cartridge (for
> direct to PCB printing) (which may or may not dry up between PCBs (I
> hate inkjets!)) or a couple bucks for special transfer paper or
> transparency paper. Couple bucks for drill bits. Couple bucks for
> tool to cut the PCB material. Moderate amount for an inkjet printer
> to modify, or for a laminator, or for an iron, or for a contact
> exposure frame. Couple buck for other chemicals, sandpaper, etc.

And not having plated holes, decent design rules like at least 8/8 mils
needed for modern packages, no silkscreen, no soldermask. When you really
add it up, you're probably paying yourself less than $10/hour to make your
own boards.

If you're really a hobbyist and claiming your time is worth little, then why
is fast turnaround so important? I do this professionally where time=money,
and 1 1/2 weeks to get the boards back is rarely a problem. That gives you
just about the right time to put the BOM together, order parts without extra
fast shipping, and have everything arrive at about the same time. Meanwhile
you work on other projects. Surely you've got something else useful to do
while you're waiting for the boards and parts to show up?

If you're constantly finding yourself doing quick turns of PCBs internally,
then you should examine your proceedures. The instant gratification of
quick turn may feel good, but I strongly suspect it doesn't make business
sense in most situations. A place that does that regularly probably has
immature engineers that don't know how to get the most out of each prototype
or are a little OCD in that they want to spin the board the moment a cut or
jumper is added to the existing one.

I find we usually do 3 PCB versions, sometimes 2, for most project. The
first is usually a bench test unit that ignores the final mechanicals.
Parts are deliberately spaced out with extra test pads, LEDs, and the like
added to aid debugging and possible modifications. Usually this includes
the largest PIC of the subfamily. Most of the development is done with this
board. The second version is designed to be the shippable product. Now we
get rid of extraneous LEDs, use the right size PIC which we know since the
firmware is mostly working, add the inevitable little things to accomodate
spec changes, etc. Often the customer will change some specs after this
board because this is the first time others in the company get to see full
mockup units. We let this settle out a bit and the third version is usually
the first production version. Respins are not that expensive if you manage
the process properly and especially when you plan on them up front.

On Wed, Mar 23, 2011 at 08:06:28AM -0400, Olin Lathrop wrote:
> 'William Chops" Westfield ' <@spam@westfw@spam@spam_OUTmac.com wrote:
> > It depends. Couple bucks for blank copper clad. Couple bucks for
> > etchant. Significant bucks for the high-grade ink cartridge (for
> > direct to PCB printing) (which may or may not dry up between PCBs (I
> > hate inkjets!)) or a couple bucks for special transfer paper or
> > transparency paper. Couple bucks for drill bits. Couple bucks for
> > tool to cut the PCB material. Moderate amount for an inkjet printer
> > to modify, or for a laminator, or for an iron, or for a contact
> > exposure frame. Couple buck for other chemicals, sandpaper, etc.
>
Olin I figured you would wander by this thread eventually. I'll take a
crack at it. This is purely from a hobby perspective. So there should be no
professional attribution applied to it.

> And not having plated holes, decent design rules like at least 8/8 mils
> needed for modern packages, no silkscreen, no soldermask. When you really
> add it up, you're probably paying yourself less than $10/hour to make your
> own boards.

Since it's a hobby, neither making money, or trying to attribute money to
the time applies. Hobbyist do the job because it's fun for them, not work.

> If you're really a hobbyist and claiming your time is worth little, then why
> is fast turnaround so important?

Simple: because a hobbyist wants to see the results ASAP. This isn't
consulting where there's other work to do while waiting around (which you
point out below). Whatever project a hobbyist is working on is the sole
focus of the hobby at the time. So waiting around is neither productive nor
fun.

> I do this professionally where time=money,
> and 1 1/2 weeks to get the boards back is rarely a problem. That gives you
> just about the right time to put the BOM together, order parts without extra
> fast shipping, and have everything arrive at about the same time. Meanwhile
> you work on other projects. Surely you've got something else useful to do
> while you're waiting for the boards and parts to show up?

But this isn't a profession, so none of that applies. There isn't any other
project to work on. Parts are in the junk box. Production is a one off. So
getting it out the way as quickly as possible, and getting the instant
gratification you alluded to below is in fact the objective of the hobby.

>
> If you're constantly finding yourself doing quick turns of PCBs internally,
> then you should examine your proceedures. The instant gratification of
> quick turn may feel good, but I strongly suspect it doesn't make business
> sense in most situations. A place that does that regularly probably has
> immature engineers that don't know how to get the most out of each prototype
> or are a little OCD in that they want to spin the board the moment a cut or
> jumper is added to the existing one.

All of these are professional prospectives, and make perfect sense in that
venue because the objective is to maximize the use of time to leverage it
to make money.

But with a hobby, it's for fun. An idea pops into the hoobyist head, and
the focus is to realize it ASAP. First crack is usually on a breadboard, do
some noodling to get an idea of how to put it together. While this is fine
for quick and dirty development, eventually the late alpha or early beta
needs to be transferred to permanent media. This is where the quick
turnaround comes in. Note there's no BOM to deal with, because all the
parts needed for the project are now on the B&D breadboard prototype.

or others like it. Works for the core controller and its associated
electronics. But then it's back to point to point wiring for the project
specific stuff.

As a hobbyist, neither the process of waiting around for the project to
come together, nor the tedious process of assembly are very gratifying. For
a real job, for real money, it's work and you suck it up. But I already
have a real job, with real work (a lot of it tedious). So if I'm doing
something fun, the last thing I want is for it to look like work.

In my ideal hobby world, a project would consist of using a tool like Eagle
or Kicad to capture the project schematic, produce the board and a solder
stencil mask from the design, etch both (board on PCB, stencil mask on
brass or steel), slather the solder paste via the mask, populate, then
grill the components to the board using a hot plate. Two hours tops from
start to finish.

>
> I find we usually do 3 PCB versions, sometimes 2, for most project. The
> first is usually a bench test unit that ignores the final mechanicals.
> Parts are deliberately spaced out with extra test pads, LEDs, and the like
> added to aid debugging and possible modifications. Usually this includes
> the largest PIC of the subfamily. Most of the development is done with this
> board. The second version is designed to be the shippable product. Now we
> get rid of extraneous LEDs, use the right size PIC which we know since the
> firmware is mostly working, add the inevitable little things to accomodate
> spec changes, etc. Often the customer will change some specs after this
> board because this is the first time others in the company get to see full
> mockup units. We let this settle out a bit and the third version is usually
> the first production version. Respins are not that expensive if you manage
> the process properly and especially when you plan on them up front.

Sounds like a great professional job. But why would a hobbyist who needs
exactly one of these go through this process? Only the first version is
necessary because it's not for sale.

The hobby objective is not to build a sellable product. The objective is to
come up with a permanent realization of an idea with as little hassle as
possible, as quickly as possible. Cost effective would be nice too, as long
as it doesn't create a hassle.

The true difference between a professional and a hobbyist is that a
professional is paid to overcome project obstacles in a timely fashion.
With a hobbyist, obsticles kills projects, because the project is a
realization of an idea or a dream that has no cost basis attached to it.

Some snippage...
> > So what you only really need is the copper board. Everything is already
> > lying around somewhere or will last "forever" or costs pennies.
> >
>
> I agree, there is a startup cost, but that cost is very cheap and probably
> less than the cost of a decent sized professionally made PCB. I'd seriously
> rather make them myself. 30 seconds to print, a few minutes to iron, a few
> minutes to etch, a few minutes to drill/sand and there you have it. I can
> have a design to end product in 30 minutes (done so a few times already).
> And for small things, that's priceless.

I'm looking to get around the drilling and soldering by moving to surfact
mount, etching a solder mask stencil, solder pasting the board, then
grilling it on a hot plate. The solder mask stencil can be created and etched exactly
the same way as the PCB, so you get a 2-for-1.

Trying to get a perspective from Olin of how his processes are different
from professional work vs. doing something for a hobby. Since embedded
systems engineering is his real job, it's unlikely that it's also his
hobby.

> On Wed, Mar 23, 2011 at 10:17:55AM -0400, Mark E. Skeels wrote:
>> [SNIP....]
>>
>> BTW Olin, what do you do for a hobby?
>>
>> ??????
> Trying to get a perspective from Olin of how his processes are different
> from professional work vs. doing something for a hobby. Since embedded
> systems engineering is his real job, it's unlikely that it's also his
> hobby.
>

> If you're really a hobbyist and claiming your time is worth little,
> then why is fast turnaround so important?

Speaking from my own motivations for the LPKF, one of the issues is that as a hobbyist I didn't have a lot of confidence in my ability to design a board that would work. So it wasn't so much a matter of sending off $50 for more boards than I could use, it was also the conviction that those boards wouldn't work, and so I'd have to do it again! Probably several times.

And then there's the "urge to tweak." Having immediate turnaround lets you fiddle with a board design until it's not just working, but "perfect."

'William Chops" Westfield ' <spamBeGonewestfwKILLspammac.com wrote:
> And then there's the "urge to tweak." Having immediate turnaround
> lets you fiddle with a board design until it's not just working, but
> "perfect."

I think it's just about what works best for people, horses for courses and all that..
Hobbyist or business, it seems that (some) people find there is some benefit to making their own boards.
Whether this is the "best" way is almost impossible to judge, given the huge range of EE and number of factors to consider. I think comparing methods of work/production of say, vintage audio (tube amps, through hole, point to point, etc) with multilayer, high speed, low power, SMD design, would be a little difficult.

> And not having plated holes, decent design rules like at least 8/8 mils
> needed for modern packages, no silkscreen, no soldermask. When you really
> add it up, you're probably paying yourself less than $10/hour to make your
> own boards.

I started off using the professionally-made "Press-n-Peel" sheets by Techniks with my laser printer. The results were completely satisfactory and probably better than I could have done with plain transparencies or whatever. I was all excited and ready to fab my own boards for my hobby work, even got pretty good at two-sided boards done that way.

And then I tried sending a board out to a real fab once. IMHO, it's totally worth it to get a high quality, plated, drilled, masked board. I haven't touched my etchant tank since.

Hi ... my 2c on all this. I agree with Olin and the projects I do follow the same arc of prototyping/revise/production with BOM finalizing, initial firmware development, etc. etc.

At one point long ago, I had the special paper to laserprint onto, spent $200 for a laminator, have a dremel with set of 30 fine drillbits and mini drill press, etc. I could do a design + layout and transfer, etch, drill, fix etch problems, solder parts, and get something going in a day or less for a simple thing.

And for all the reasons Olin mentioned, I gave away all this gear (to Limor Fried of all people, aka lady ada, who has gone from making pcbs to buying a pick and place for her very successful biz and is now on the cover of Wired of all things) and never looked back and never wished I still had any of it, 7 years later.

Because for all the reasons Olin mentioned it is not worth doing in a professional context, with the possible exception of RF design work, and that's a specialized field.

For the enjoyment of the craft of it all, to fiddle around, have your hands dirty (stained, actually, in this case) with as much DIY hands on fun as one can with electronics, its great. This is not to be confused with professional work. I know zero, that's zero, people who make their own boards and bill that time to a client. Solarwind is in school; other people do it as a hobby; part of the fun is seeing how cheap you can be with it all. Can I make something in an afternoon for $6? A game.

Around the point where it became clear that DIY pcbs were incompatible with a career in electronics, I found barebonespcb.com, and that sealed the deal - most of the fast turnaround DIY gets, but made with regular industrial pcb manufacturing equipment so you can do normal design rules. Highly recommended. I've done probably 60 designs with them as the prototype phase.

Anyway, that's my 2c. Been there with DIY pcbs, never again, but it obviously depends on what one's intent with it all is. This year I'm going to set up the garage to do basic metalwork kind of stuff, get a used milling machine of some sort, have a cheap drill press, maybe some welding gear, etc. A machinist or metal fabricator would look at it all and say ugh, seriously? and he'd be right. But all I want to do is make metal whatnots for some hobby-grade robotics and the like. If I were billing per hour to build my stuff, I'd outsource all the fabrication.

If solarwind over time moves a couple rungs up the ladder in terms of design sophistication and need to have repeatable production / stable project timelines, there will necessarily be the rather modest additional funding to achieve this. DIY boards will no longer be sensible. But by doing it the fun, sometimes hard way, he'll be real good at continuity checking, finding faults fast visually, xacto knife cuts and scraping, soldering in inconvenient situations, etc. etc. This will serve anyone who does hands-on electronics design well.

> 'William Chops" Westfield '<TakeThisOuTwestfwKILLspamspammac.com wrote:
>> It depends. Couple bucks for blank copper clad. Couple bucks for
>> etchant. Significant bucks for the high-grade ink cartridge (for
>> direct to PCB printing) (which may or may not dry up between PCBs (I
>> hate inkjets!)) or a couple bucks for special transfer paper or
>> transparency paper. Couple bucks for drill bits. Couple bucks for
>> tool to cut the PCB material. Moderate amount for an inkjet printer
>> to modify, or for a laminator, or for an iron, or for a contact
>> exposure frame. Couple buck for other chemicals, sandpaper, etc.
>
> And not having plated holes, decent design rules like at least 8/8 mils
> needed for modern packages, no silkscreen, no soldermask. When you really
> add it up, you're probably paying yourself less than $10/hour to make your
> own boards.
>
> If you're really a hobbyist and claiming your time is worth little, then why
> is fast turnaround so important? I do this professionally where time=money,
> and 1 1/2 weeks to get the boards back is rarely a problem. That gives you
> just about the right time to put the BOM together, order parts without extra
> fast shipping, and have everything arrive at about the same time. Meanwhile
> you work on other projects. Surely you've got something else useful to do

In a wider sense, DIY is real hands-on character and skill
development. So much is done 'for' people rather than 'by'
people, perhaps no more so than in previous generations but
these days if you want anything done, no matter how trivial,
chances are there is someone on the web who'll do it. As a
very practical person who likes using my brain and tools,
perhaps I'm biased. And of course I do things for other people
who don't have the relevant skills, but generally more than others
do for me

> > But by doing it the fun, sometimes hard way, he'll be real
> > good at continuity checking, finding faults fast visually, xacto
> > knife cuts and scraping, soldering in inconvenient situations,
> > etc. etc. This will serve anyone who does hands-on electronics
> > design well.
>
> In a wider sense, DIY is real hands-on character and skill
> development. So much is done 'for' people rather than 'by'
> people, perhaps no more so than in previous generations but
> these days if you want anything done, no matter how trivial,
> chances are there is someone on the web who'll do it. As a
> very practical person who likes using my brain and tools,
> perhaps I'm biased. And of course I do things for other people
> who don't have the relevant skills, but generally more than others
> do for me

Not only that, but you get an appreciation for what is required in the manufacture, and when a board house says that this feature on your payout is going to cost an extra 10% you will have a feel for why. Having done the DIY manufacture yourself you get a feel for what helps the commercial guy when you are doing your layout.
-- Scanned by iCritical.

The April issue of Circuit Cellar arrived this morning, one of the items being advertised by http://www.parallax.com/ is a 'pen robot' which shows a sharpie type pen poked into a robot thingie to draw pictures.

My immediate thought was this thread, and someone attempting to get it to draw pen resist on a PCB blank instead of a conventional plotter ...
-- Scanned by iCritical.

> The April issue of Circuit Cellar arrived this morning, one of the items
> being advertised by http://www.parallax.com/ is a 'pen robot' which shows
> a sharpie type pen poked into a robot thingie to draw pictures.
>
> My immediate thought was this thread, and someone attempting to get it to
> draw pen resist on a PCB blank instead of a conventional plotter ...
>

OT.

Propellers are so cool. I never knew they were 32 bit processors. I can
think of lots of uses for these babies

IVP wrote:
> In a wider sense, DIY is real hands-on character and skill
> development. So much is done 'for' people rather than 'by'
> people, perhaps no more so than in previous generations but
> these days if you want anything done, no matter how trivial,
> chances are there is someone on the web who'll do it.

Which leaves you free to do yet something else, something presumably you
enjoy more or can add more value to than the task you farmed out. In fact
one could argue that you are doing the world a net disservice by not
sticking to what you are particularly good at, and thereby letting others do
what they are good at.

....that is the usual reaction, but they haven't gained much traction in the industry. I think their clever, useful, but unorthodox architecture makes them a risk for a lot of commercial designs. No way to swap it for a competitor's chip and tweak code a little if supply lead-times gets long. Etc. A hassle to do for any microcontroller, but impossible when using a propeller.

For high-end hobby, its pretty fantastic.

For advancing one's career in the EE design world, I suggest getting into FPGAs.

My 2c!
J

V G wrote:
>
> Propellers are so cool. I never knew they were 32 bit processors. I can
> think of lots of uses for these babies